How to sort database by two fields?

Question

MySQL

Good afternoon, there are 2 fields in the table by which you need to sort
category_id and cname
in category_id can be empty or some kind of digital value, names are written in cname.
you need to sort so that it would first give out empty spaces from category_id corresponding to the value in cname alphabetically, and then where there are values ​​in category_id, also in accordance with cname alphabetically
, I tried it and so ORDER BY `category_id`, `cname` and so ORDER BY ` cname`, `category_id` does not work properly.

Answer 1

ORDER BY `category_id` IS NOT NULL, `cname`